1. Field of the Invention
This invention relates to a butterfly valve for controlling flow therethrough of a high temperature fluid and to a method of making such a valve.
2. Prior Art Statement
Butterfly valves are well known in the art and are used in numerous applications to control the flow of various fluids therethrough. Also, in applications such as electrical power generating stations, refineries, and the like, the need exists for such valves which are capable of operating for long periods of time while controlling high temperature fluids flowing therethrough. In the above applications, such butterfly valves may be of comparatively large size, often having an effective flow diameter of several feet, and even larger.
It is also known in the art to provide a butterfly valve for controlling flow of fluid therethrough wherein the valve comprises an outer metal housing, a ceramic lining carried by the housing and defining a fluid flow passage through the valve, a valve closure member, a rotatable shaft fixed to the member, and means rotatably supporting the shaft on the housing to enable rotation of the member within the flow passage from an open to a closed position to open and close the flow passage.
However, the butterfly valves which have been proposed heretofore to control the flow of fluids therethrough wherein such fluids are at elevated temperatures generally of the order of 2,500.degree. F. have various deficiencies. One deficiency with each of such valves is that the valve closure member thereof tends to be eroded and/or corroded by the high temperature fluid flowing therethrough. Another deficiency is the tendency for the supporting portions of the closure member to fail prematurely due to the high temperatures. Another deficiency is that each of such valves requires substantial cooling using coolants, such as, water, air, steam, and the like, in order to assure satisfactory operation. Another deficiency is the failure of previous valves because metal components thereof are not effectively isolated and thermally insulated.
It is an object of this invention to provide an improved butterfly valve capable of operating at elevated temperatures of the character mentioned for an extended service life.
Another object of this invention is to provide an improved method of making such a butterfly valve.
Other aspects, embodiments, objects, and advantages of this invention will become apparent from the following specification, claims, and drawings.